Non-intrusion type charging system for artificial organ, capacitor and power supplying device used in the system

ABSTRACT

According a charging system of this invention, an AC required for charging of an electric double layer capacitor of a storage device in the body may be transmitted from a feeding device outside the body through power receiving and power transmitting coils. The electric double layer capacitor may be charged in a contactless mode, without incising the body of the artificial organ user, while the storage device remains embedded in the body. The electric double layer capacitor may be charged reliably by avoiding a shortage of charging since the charge status of the electric double layer capacitor of the storage device is known during a charging operation.

TECHNICAL FIELD

This invention relates to a charging system for an artificial organhaving a storage device embedded in the body along with the artificialorgan to act as an artificial organ driving power source, and a feedingdevice for feeding power to the storage device, and particularly to atechnique for enabling a reliable charging in a contactless mode of thestorage device remaining embedded in the body.

BACKGROUND ART

Conventionally, a cardiac pacemaker (hereinafter referred to simply as“pacemaker” where appropriate) exists as one of the artificial organs.The pacemaker is embedded in the body with a battery acting as drivingpower source. The pacemaker embedded in the body, while receiving asupply of driving electric power from the battery, causes the heart tobeat regularly by directly applying an electrical pulse to andstimulating the heart. A nickel cadmium cell, lithium cell or the likeis used for the battery acting as the driving power source of thecardiac pacemaker. The pacemaker maker continues applying an electricalpulse to the heart until the life of the battery runs out.

However, in the case of the above conventional example, there is aproblem that the battery cannot be charged from outside the body whilethe battery remains embedded in the body. That is, since the batteryremaining embedded in the body cannot be charged, when the life of thebattery runs out, it is necessary to perform an operation to incise thebody of the user of the artificial cardiac pacemaker, take the batteryout of the body, and embed a new battery as replacement. However, thebattery changing operation for incising the body imposes a heavy burdenespecially on a person having trouble with the heart.

This invention has been made having regard to the state of the art notedabove, and its object is to provide a contactless charging system for anartificial organ, and a storage device and a feeding device for use withthis system, in which the storage device embedded in the body along withthe artificial organ to act as an artificial organ driving power source,while remaining embedded in the body, may be charged reliably in acontactless mode from outside the body (without incising the body).

DISCLOSURE OF THE INVENTION

A contactless charging system for an artificial organ, according to thisinvention, is characterized by comprising a storage device embedded as awhole in a body along with the artificial organ, and including powerreceiving coil means acting as a secondary side coil in a pair of coilmeans for transferring power, rectifying means for rectifying andoutputting an AC received by the power receiving coil means, storagemeans for storing output from the rectifying means as electric power fordriving the artificial organ, charge status detecting means for detect acharge status of the storage means, and charge status transmitting meansfor transmitting outside the body the charge status detected by thecharge status detecting means; and a feeding device provided separatelyfrom the storage device and disposed as a whole outside the body, andincluding power transmitting coil means acting as a primary side coil insaid pair of coil means, AC output means for outputting the AC to thepower transmitting coil means, charge status receiving means forreceiving the charge status transmitted outside the body from saidcharge status transmitting means, and charge status informing means forinforming the charge status received by the charge status receivingmeans.

According to the contactless charging system for an artificial organ ofthis invention, in time of charging by the contactless charging systemfor an artificial organ (hereinafter called simply “charging system” asappropriate), the feeding device provided separately from the storagedevice and disposed as a whole outside the body is used to charge thestorage device embedded as a whole in the body along with the artificialorgan, as follows.

The charging system is operated, by setting the power transmitting coilmeans of the feeding device acting as a primary side coil in the pair ofcoil means for transferring power, and the power receiving coil means ofthe storage device acting as a secondary side coil in the pair of coilmeans, so that the two coil means are capable of transferring power byelectromagnetic coupling, electromagnetic induction or electromagneticwave. Then, the AC required for the charging outputted from the ACoutput means of the feeding device is transmitted from the powertransmitting coil means outside the body to the storage device insidethe body. The AC transmitted from the power transmitting coil means isreceived by the power receiving coil means inside the body, rectified bythe rectifying means, and then fed to the storage means. In the storagemeans, the output from the rectifying means is stored as artificialorgan driving power.

On the other hand, the charge status of the storage means of the storagedevice is detected by the charge status detecting means, and transmittedoutside the body by the charge status transmitting means. The chargestatus transmitted outside the body is received by the charge statusreceiving means of the feeding device, and is reported by the chargestatus informing means. The charge status of the storage means of thestorage device is checked outside the body through the report on chargestatus. The charging will be completed when the charge status reaches apredetermined state.

As described above, the AC required for charging is transmitted from thepower transmitting coil means outside the body acting as a primary sidecoil to the power receiving coil means inside the body acting as asecondary side coil, in the form of electromagnetic coupling,electromagnetic induction or electromagnetic wave. As a result, thestorage means may be charged in a contactless mode from outside thebody, without incising the body, while the storage device remainsembedded in the body.

The charge status of the storage means in the storage device is detectedin the storage device inside the body and transmitted outside the body,and is received and reported by the feeding device outside the body.Thus, the charge status of the storage means may be checked duringcharging. As a result, a shortage of charging is avoided and the storagemeans may be charged reliably.

In the contactless charging system for an artificial organ according tothis invention, at least one of the storage device and the feedingdevice includes amount of coil displacement detecting means fordetecting an amount of coil displacement as an extent of a displacementoccurring between the power receiving coil means and the powertransmitting coil means, and the feeding device includes amount of coildisplacement informing means for informing the amount of coildisplacement detected by the amount of coil displacement detectingmeans.

For example, the amount of coil displacement detecting means of thestorage device includes a smoothing circuit for smoothing a voltage atopposite ends of the power receiving coil detecting means, and asecondary side control circuit for determining the amount of coildisplacement based on a smoothed voltage value. The amount of coildisplacement detecting means of the feeding device includes a smoothingcircuit for smoothing a voltage at opposite ends of the powertransmitting coil detecting means, and a primary side control circuitfor determining the amount of coil displacement based on a smoothedvoltage value.

That is, the amount of coil displacement between the power receivingcoil means and power transmitting coil means is detected by the amountof coil displacement detecting means, and is reported by the amount ofcoil displacement informing means outside the body. It is thus possibleto know the extent of the displacement between the power receiving coilmeans and power transmitting coil means. Since both coils can be set toproper positions by resetting both the coil means according to theextent of the displacement, charging of the storage device may becarried out efficiently.

In the contactless charging system for an artificial organ according tothis invention, it is preferable that the amount of coil displacementdetecting means is disposed in the storage device, the amount of coildisplacement detected being transmitted outside the body along with thecharge status by the charge status transmitting means. It is furtherpreferable that display means is provided for displaying the amount ofcoil displacement and the charge status transmitted outside the body bythe charge status transmitting means.

That is, the amount of coil displacement detecting means is disposed inthe storage device, and the amount of coil displacement detected istransmitted outside the body along with the charge status by using thecharge status transmitting means. It is thus possible to avoidcomplication of the device construction. By displaying the amount ofcoil displacement on the display means, a positional adjustment of thepower receiving coil means and power transmitting coil means may becarried out easily for correction of the amount of coil displacement.

In the contactless charging system for an artificial organ according tothis invention, it is preferable that at least one of the storage deviceand the feeding device includes direction of coil displacement detectingmeans for detecting a direction of coil displacement as an extent of adisplacement occurring between the power receiving coil means and thepower transmitting coil means, and that the feeding device includesdirection of coil displacement informing means for informing thedirection of coil displacement detected by the direction of coildisplacement detecting means.

For example, the direction of coil displacement detecting means of thestorage device includes a plurality of direction detecting coilsarranged at predetermined intervals around the power receiving coilmeans, and a secondary side control circuit for determining thedirection of coil displacement based on voltages values detected fromthe plurality of direction detecting coils. The direction of coildisplacement detecting means of the storage device includes a pluralityof direction detecting coils arranged at predetermined intervals aroundthe power receiving coil means, and a primary side control circuit fordetermining the direction of coil displacement based on voltages valuesdetected from the plurality of direction detecting coils.

The direction of coil displacement detecting means of the storage devicemay include a plurality of divided power receiving coil means arrangedannularly, and a secondary side control circuit for determining thedirection of coil displacement based on voltages values detected fromthe respective power receiving coil means. The direction of coildisplacement detecting means of the storage device may include aplurality of divided power receiving coil means arranged annularly, anda primary side control circuit for determining the direction of coildisplacement based on voltages values detected from the respective powerreceiving coil means.

With the above construction, the direction of coil displacement betweenthe power receiving coil means and power transmitting coil means isdetected by the direction of coil displacement detecting means, and isreported by the direction of coil displacement informing means outsidethe body. It is thus possible to know the direction of the displacementbetween the power receiving coil means and power transmitting coilmeans. Therefore, the displacement between the power receiving coilmeans and power transmitting coil means may be corrected easily.

In the contactless charging system for an artificial organ according tothis invention, it is preferable that the direction of coil displacementdetecting means is disposed in the storage device, the direction of coildisplacement detected being transmitted outside the body along with thecharge status by the charge status transmitting means. It is furtherpreferable that display means is provided for displaying the directionof coil displacement and the charge status transmitted outside the bodyby said charge status transmitting means.

That is, the direction of coil displacement detecting means is disposedin the storage device, and the direction of coil displacement detectedis transmitted outside the body along with the charge status by usingthe charge status transmitting means. It is thus possible to avoidcomplication of the device construction. By displaying the direction ofcoil displacement on the display means, a positional adjustment of thepower receiving coil means and power transmitting coil means may becarried out easily for correction of the direction of coil displacement.

In the contactless charging system for an artificial organ according tothis invention, it is preferable that the storage means of the storagedevice is a rechargeable battery or an electric double layer capacitor.Where, for example, an electric double layer capacitor is used, which issmall but has a large capacity, it is compact and has a sufficientstorage function, has a long life with little deterioration or the likeby repeated charging, and moreover is low in heat generation. Thus, thestorage means in the form of an electric double layer capacitor isbetter than other, rechargeable batteries and the like.

A storage device for use with a contactless charging system for anartificial organ according to this invention, preferably, is a storagedevice having the above-described construction. That is, the storagedevice may be used with the contactless charging system, such that thestorage device acting as artificial organ driving power source isreliably chargeable in a contactless mode while remaining embedded inthe body.

A feeding device for use with a contactless charging system for anartificial organ according to this invention, preferably, is a feedingdevice having the above-described construction. That is, the feedingdevice may be used with the contactless charging system, such that thestorage device acting as artificial organ driving power source isreliably chargeable in a contactless mode while remaining embedded inthe body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an entire construction of a chargingsystem according to an embodiment;

FIG. 2 is a schematic view showing a situation in time of charging bythe charging system in the embodiment;

FIG. 3 is a time chart showing an allocation of detection resulttransfer periods in time of charging;

FIG. 4 is a table chart showing a relationship between charge voltagerange and pulse ration number;

FIG. 5 is a time chart illustrating a transfer/detection situation ofcharge state in the embodiment;

FIG. 6 is a time chart illustrating a transfer/detection situation ofcharge state in the embodiment;

FIG. 7 is a table chart showing a relationship between factors on asecondary side relating to coil displacement;

FIG. 8 is a table chart showing a relationship between primary side andsecondary side relating to coil displacement;

FIG. 9 is a flow chart showing a progress of charging by the chargingsystem in the embodiment;

FIG. 10 is a graph showing changes with time of charge status by thecharging system in a charging experiment;

FIG. 11 is a graph showing changes with time of charge status by thecharging system in a charging experiment;

FIG. 12 is a block diagram showing a construction for detecting adirection of coil displacement in a charging system in anotherembodiment;

FIG. 13 is a table chart showing a relationship between direction ofcoil displacement and pulse ration number; and

FIG. 14 is a time chart showing an allocation of direction of coildisplacement transfer periods in time of charging.

BEST MODE FOR CARRYING OUT THE INVENTION

Modes for solving the problem of the prior art include the following.

An embodiment of this invention will be described hereinafter withreference to the drawings.

An embodiment of each of a contactless charging system for an artificialorgan, and a storage device and a feeding device for use with thissystem, according to this invention, will be described hereinafter. FIG.1 is a block diagram showing an entire construction of the chargingsystem according to the embodiment. FIG. 2 is a schematic view showing asituation in time of charging by the charging system in the embodiment.

The charging system in the embodiment, as shown in FIGS. 1 and 2,includes a storage device 1 wholly embedded, as molded in a siliconeresin or the like together with a cardiac pacemaker 3 acting as anartificial organ, for example, in the body of a user M of the pacemaker3, and a feeding device formed separately from this storage device 1 anddisposed as a whole outside the body of the user M carrying thepacemaker 3. In the body of the user M, the pacemaker 3, while receivinga supply of driving electric power from the storage device 1, causes theheart of the user M to continue beating regularly by directly applyingan electrical pulse to and stimulating the heart.

The storage device 1 includes a power receiving coil (power receivingcoil means) 4 acting as a secondary side coil in a pair of powertransfer coils, a full wave rectification bridge (rectifying means) 5for rectifying and outputting an AC received by the power receiving coil4, and an electric double layer capacitor (storage means) 6 chargeablewith the output from the full wave rectification bridge 5 to storepacemaker driving electric power. A ripple removing capacitor 7 and areverse current preventing diode 8 are arranged between the full waverectification bridge 5 and electric double layer capacitor (EDLC) 6.

The feeding device 2 includes a power transmitting coil (powertransmitting coil means) 9 acting as a primary side coil in the pair ofpower transfer coils, an AC oscillator (AC output means) 10 foroutputting an AC with a frequency of about 100 kHz to 2 GHz to thispower transmitting coil 9. The power transmitting coil 9 is connected toa main body case 2A by a cable 9A to be freely movable. The powerreceiving coil 4 and power transmitting coil 9 usually have a diameterof about 20-50 mm, the power transmitting coil 9 being slightly larger.

When a charging operation is carried out by the charging system in theembodiment, the charging system is started after setting the powertransmitting coil 9 of the feeding device 2 outside the body to aposition opposed to the power receiving coil 4 of the storage device 1inside the body so that the power receiving and power transmitting coils4 and 9 may transfer power by electromagnetic coupling, electromagneticinduction or electromagnetic wave. Then, the AC required for thecharging outputted from the AC oscillator 10 of the feeding device 2 istransmitted from the power transmitting coil 9 outside the body to thestorage device 1 inside the body. The AC transmitted from the powertransmitting coil 9 is received by the power receiving coil 4 inside thebody, rectified by the full wave rectification bridge 5, and then fed tothe electric double layer capacitor 6. In the electric double layercapacitor 6, pacemaker driving power is stored by the output from thefull wave rectification bridge 5. The electric double layer capacitor(storage means) 6, although small, has a large capacity, therefore iscompact and has a sufficient storage function, has a long life withlittle deterioration or the like by repeated charging, and moreover islow in heat generation. It is therefore better suited than other,rechargeable batteries and the like.

The storage device 1 includes a voltage monitor circuit (charge statusdetecting means) 11 for detecting a charge voltage indicative of acharge status of the electric double layer capacitor 6. This voltagemonitor circuit 11 is arranged to output the detected charge voltage ofthe electric double layer capacitor 6 to a secondary side controlcircuit 12, and to stop the charging automatically when the chargevoltage of the electric double layer capacitor 6 reaches 2.3V which isan operating voltage of the pacemaker 3. In this embodiment, theelectric double layer capacitor 6 has a withstand voltage of 2.5V, andtherefore an upper limit of the charge voltage of the electric doublelayer capacitor 6 is set to 2.3V which is a voltage below the withstandvoltage.

The secondary side control circuit 12, as described hereinafter, acts ascharge status transmitting means for cooperating with a resonancecircuit 13 to transmit outside the body a charge status corresponding tothe charge voltage detected by the voltage monitor circuit 11. Theresonance circuit 13 is formed of the power receiving coil 4, and acapacitor 13A and a digital variable resistor 13B connected in paralleltherewith. The power transfer action of the power receiving and powertransmitting coils 4 and 9, essentially, is performed under resonantconditions. The digital variable resistor 13B is a resistor having aresistance discretely (stepwise) changeable by a digital signaloutputted from the secondary side control circuit 12. A resonantcondition caused by the resonance circuit 13 is changeable stepwise,with a change of the digital variable resistor 13B, from a full resonantcondition to a virtually absolutely non-resonant condition. This changein the resonant condition on the secondary side by the resonance circuit13 is transmitted from the power receiving coil 4 to the primary sidethrough the power transmitting coil 9. A voltage at opposite ends of thepower transmitting coil 9 varies according to levels of the resonantcondition, and this is used to transmit the charge status of theelectric double layer capacitor 6 outside the body.

On the one hand, in the case of the charging process of the chargingsystem according to the embodiment, as shown in FIG. 3, a detectionresult communicating period is set after every fixed charging period.The first half of the detection result communicating period is set as acharge status communicating period. And during a charging executionperiod, a digital signal is transmitted from the secondary side controlcircuit 12 to the variable resistor 13B to set a resistance to thedigital variable resistor 13B to make the resonant condition by theresonance circuit 13 the full resonant condition over the entire period.During the charging execution period, charging power is transmittedefficiently with the resonant condition by the resonance circuit 13 inthe full resonant condition over the entire period.

On the other hand, in the secondary side control circuit 12, as shown inFIG. 4, the charge voltage range (0V -2.3V) of the electric double layercapacitor 6 is divided into eight stages corresponding to the numbers ofpulses 1 to 8, and a charge status is transmitted outside the body frominside the body by transmitting to the feeding device 2 the number ofpulses corresponding to the charge voltage of the electric double layercapacitor 6 detected by the voltage monitor circuit 11 during one chargestatus communicating period. Specifically, during one charge statuscommunicating period, a circuit operation, in which a digital signal istransmitted from the secondary side control circuit 12 to the digitalvariable resistor 13B so that the variable resistor 13B has a resistanceto make the resonant condition by the resonance circuit 13 theabsolutely non-resonant condition only for a predetermined short periodof time, is repeated so that the number of pulses corresponding to thecharge voltage may be outputted.

The charge status of the electric double layer capacitor 6 transmittedoutside the body from inside the body in the form of pulse as describedabove, is detected based on a voltage change at the opposite ends of thepower transmitting coil 9 of the feeding device 2 as described next.That is, a voltage at the opposite ends of the power transmitting coil 9is detected by a voltage smoothing circuit 14 including a rectifierdiode 14A, a resistance 14B and a capacitor 14C, and outputted to aprimary side control circuit 15. The primary side control circuit 15, bydetecting output changes of the voltage smoothing circuit 14, determinesa charge status (number of pulses) of the storage device 1 during onecharge status communicating period. In this embodiment, a pulse traintransmitted from the storage device is smoothed, and the number ofpulses is detected from its voltage value. However, the number of pulsesmay be counted directly.

When, as shown in FIG. 5, for example, during one charge statuscommunicating period, switching to the absolutely non-resonant conditiononly for a fixed period of the resonant condition by the resonancecircuit 13 is repeated four times, the primary side control circuit 15counts four pulses as shown in FIG. 6. And when the primary side controlcircuit 15 counts eight pulses during one charge status communicatingperiod, it is detected that the charge voltage of the electric doublelayer capacitor 6 has reached 2.3V, i.e. reached a full charge status.In the embodiment, therefore, the power transmitting coil 9, voltagesmoothing circuit 14 and primary side control circuit 15 constitute acharge status receiving means for receiving a charge status of theelectric double layer capacitor 6 transmitted outside the body frominside the body.

Further, the feeding device 2 includes a charge status display panel(charge status informing means) 16 disposed downstream of the primaryside control circuit 15 for displaying, in real time, a charge status ofthe electric double layer capacitor 6. A charge status of the electricdouble layer capacitor 6 is notified by lighting the number of lightemitting diodes 16 a corresponding to the number of pulses counted bythe primary side control circuit 15.

In the case of the charging system in the embodiment, as describedhereinafter, the storage device 1 detects an amount of displacementbetween the power receiving and power transmitting coils 4 and 9 (amountof coil displacement), and transmits the detected amount of coildisplacement outside the body through the power receiving and powertransmitting coils 4 and 9 by varying the resonant condition by theresonance circuit 13 according the detected amount of coil displacement,as when transmitting the charge status of the electric double layercapacitor 6 outside the body. The transmission efficiency of chargingpower lowers in proportion to the amount of coil displacement betweenthe power receiving and power transmitting coils 4 and 9, resulting inan extended charging time. For this reason, the displacement between thepower receiving coil 4 and power transmitting coil 9 is detected andchecked outside the body. The amount of coil displacement between thepower receiving and power transmitting coils 4 and 9 and the powertransmission efficiency between the power receiving and powertransmitting coils 4 and 9 are in inversely proportional relationship.The larger amount of coil displacement results in the lower AC voltageproduced at the opposite ends of the power receiving coil 4. That is,the voltage at the opposite ends of the power receiving coil 4 isinversely proportional to the amount of coil displacement.

In the storage device 1, the voltage at the opposite ends of the powerreceiving coil 4 corresponding to the amount of coil displacement issmoothed by a voltage smoothing circuit 17 including a rectifier diode17A, a resistance 17B and a capacitor 17C, and its voltage value isdetected by the secondary side control circuit 12. Thus, the voltagesmoothing circuit 17 and secondary side control circuit 12 correspond tothe amount of coil displacement detecting means in this invention.

On the one hand, in the secondary side control circuit 12, as shown inFIG. 7, the output voltage range of the voltage smoothing circuit 17 isdivided beforehand into five stages, for example. The respective outputvoltage divisions have, assigned thereto in order from lowest voltage,five-stage resonance levels 1 to 5 set to rise successively stage bystage from the absolutely non-resonant condition. The resonance levels 1to 5 are set so that voltage changes at the opposite ends of the powertransmitting coil 9 occurring with changes between resonance level 5 andabsolutely non-resonant condition are approximately half the voltagechanges at the opposite ends of the power transmitting coil 9 occurringwith the changes between the full resonant condition and absolutelynon-resonant condition. This is done to facilitate a determinationwhether the voltage changes at the opposite ends of the powertransmitting coil 9 are due to the communication of a charge status ordue to the communication of an amount of coil displacement. Further, asshown in FIG. 7, in the secondary side control circuit 12, digitalsignals corresponding to the resistances of the digital variableresistor 13B in time of the five-stage resonant conditions 1-5 are setto correspond to the resonant conditions 1-5.

On the other hand, in the case of the charging process of the chargingsystem in the embodiment, as shown in FIG. 3, the second half of thedetection result communicating period is set as an amount of coildisplacement communicating period. During the amount of coildisplacement communicating period, the secondary side control circuit 12recognizes a voltage division of the amount of coil displacementcorresponding to a voltage detected by the voltage smoothing circuit 17.A digital signal is transmitted from the secondary side control circuit12 to the digital variable resistor 13B so that the resonant conditionby the resonance circuit 13 may be the resonant condition correspondingto the recognized voltage division. When, for example, the voltagedetected by the voltage smoothing circuit 17 is recognized as voltagedivision (V3-V4), the resonance by the resonance circuit 13 is made theresonant condition 3.

And, as a change occurs in the resonant condition by the resonancecircuit 13 on the secondary side, a phenomenon of a change in thevoltage at the opposite ends of the power transmitting coil 9 also takesplace in the feeding device 2 which is the primary side. Then, thefeeding device 2 uses this phenomenon, and detects an amount of coildisplacement between the power receiving and power transmitting coils 4and 9 transmitted outside the body. The larger the amount of coildisplacement is, the farther away the resonant condition of theresonance circuit 13 is from the full resonant condition. Therefore, thevoltage at the opposite ends of the power transmitting coil 9 lowers inproportion to the amount of coil displacement.

Specifically, the voltage smoothing circuit 14 smoothes the voltage atthe opposite ends of the power transmitting coil 9, and the primary sidecontrol circuit 15 checks its voltage value to detect the amount of coildisplacement. In the case of the primary side control circuit 15, asshown in FIG. 8, the output voltage range of the voltage smoothingcircuit 14 is divided into five stages to correspond to the divisions ofthe output voltage range of the voltage smoothing circuit 17 (i.e.amount of coil displacement Q). The primary side control circuit 15checks a value of the voltage outputted from the voltage smoothingcircuit 14, recognizes a division corresponding thereto, and detects anamount of coil displacement.

In addition to the above, the primary side control circuit 15 checkswhether a change in the output voltage of the voltage smoothing circuit14 is the same as or half a voltage change occurring with a changebetween the full resonant condition and absolutely non-resonantcondition. If it is the same, it is recognized and processed as thecommunication of a charge status. If it is the half, it is recognizedand processed as the communication of an amount of coil displacement.Thus, an arrangement is provided to avoid confusion.

The feeding device 2 includes an amount of coil displacement displaypanel (amount of coil displacement informing means) 18 disposeddownstream of the primary side control circuit 15 for displaying anamount of coil displacement between the power receiving and powertransmitting coils 4 and 9. An amount of coil displacement is notifiedby lighting the number of light emitting diodes 18 a corresponding tothe amount of coil displacement detected by the primary side controlcircuit 15. The light emitting diodes 18 a correspond to the displaymeans of this invention.

A situation occurring when the electric double layer capacitor 6 ischarged by the charging system in the embodiment described above willnow be described with reference to the drawings. FIG. 9 is a flow chartshowing a progress of charging by the charging system in the embodiment.

[Step S1] The power transmitting coil 9 of the feeding device 2 outsidethe body is set to a position opposed to the power receiving coil 4 ofthe storage device 1 in the body.

[Step S2] The electric double layer capacitor 6 is charged as the ACoscillator 10 of the feeding device 2 starts oscillation to transmitcharging electric power.

[Step S3] When a charge status communicating period comes up, thevoltage monitor circuit 11, secondary side control circuit 12 andresonance circuit 13 cooperate to detect a charge voltage of theelectric double layer capacitor 6 and transmit the number of pulsescorresponding to the charge voltage outside the body from inside thebody through the power receiving and power transmitting coils 4 and 9.

[Step S4] In the feeding device 2, the voltage smoothing circuit 14 andprimary side control circuit 15 cooperate to detect the charge status ofthe electric double layer capacitor 6 transmitted outside the body asconverted into the number of pulses.

[Step S5] The charge status display panel 16 of the feeding device 2lights the number of light emitting diodes 16 a corresponding to thecharge status of the detected electric double layer capacitor 6.

[Step S6] When an amount of coil displacement communicating period comesup, the voltage smoothing circuit 17, secondary side control circuit 12and resonance circuit 13 cooperate to detect an amount of coildisplacement between the power receiving and power transmitting coils 4and 9, and transmit it outside the body from inside the body through thepower receiving and power transmitting coils 4 and 9.

[Step S7] In the feeding device 2, the voltage smoothing circuit 14 andprimary side control circuit 15 detect the amount of coil displacementbetween the power receiving and power transmitting coils 4 and 9transmitted outside the body.

[Step S8] The amount of coil displacement display panel 18 of thefeeding device 2 lights the number of light emitting diodes 18 acorresponding to the amount of coil displacement between the powerreceiving and power transmitting coils 4 and 9.

[Step S9] The charging operation is continued until the electric doublelayer capacitor 6 reaches a full charge status, and whenever a detectionresult communicating period comes up, steps S3-S8 are repeated tocontinue the process of detecting and informing the charge status andamount of coil displacement. During the charging operation, the operator(system driver) constantly checks the charge status of the electricdouble layer capacitor 6 on the charge status display panel 16. When theamount of coil displacement between the power receiving and powertransmitting coils 4 and 9 displayed on the amount of coil displacementdisplay panel 18 exceeds a predetermined amount, the coil displacementbetween the power receiving and power transmitting coils 4 and 9 iscorrected to transmit the charging electric power efficiently. When theelectric double layer capacitor 6 reaches the full charge status, thecharging is completed to end the charging operation by the chargingsystem.

In order to test the charging function of the charging system in theembodiment, a charging experiment has been conducted with a 10 mm thickpiece of meat placed between the power receiving and power transmittingcoils 4 and 9. The capacity of the electric double layer capacitor 6 is1F. FIG. 10 shows variations with time of the charge voltage of theelectric double layer capacitor 6 in the charging experiment. As shownin FIG. 10, the electric double layer capacitor 6 reached the fullcharge status of 2.3V 440 seconds from a start of charging.

For reference, a charging experiment has been conducted in the same waynoted above except that a mere space is left, with no meat piece placed,between the power receiving and power transmitting coils 4 and 9. FIG.11 shows variations with time of the charge voltage of the electricdouble layer capacitor 6 in this charging experiment. As shown in FIG.11, the electric double layer capacitor 6 reached the full charge statusof 2.3V 228 seconds from a start of charging.

From the above charging experiment, it has been confirmed that, in thecase of the charging system in the embodiment, when an object of skinthickness is interposed between the power receiving and powertransmitting coils 4 and 9, a charging function suited for practical useis fully demonstrated although the charging time is somewhat extended.

Thus, according to the charging system in the embodiment, the ACrequired for charging of the storage device 1 in the body may betransmitted from outside the body in the form of electromagneticcoupling, electromagnetic induction or electromagnetic wave. Theelectric double layer capacitor 6 may be charged in a contactless modefrom outside the body, without incising the body, while the storagedevice 1 remains embedded in the body. Charging may be carried outreliably since the operator can check the charge status of the electricdouble layer capacitor 6 of the storage device 1 during a chargingoperation. In the case of the charging system in the embodiment, sincethe operator can know an amount of coil displacement between the powerreceiving and power transmitting coils 4 and 9, charging may be carriedout efficiently by correcting the coil displacement between the powerreceiving and power transmitting coils 4 and 9.

A different embodiment of this invention will be described next. In acharging system according to the different embodiment, the storagedevice 1 detects a direction of displacement occurring between the powerreceiving coil 4 and power transmitting coil 9 (direction of coildisplacement), and transmits it outside the body from inside the body.The feeding device 2 detects and informs the direction of coildisplacement transmitted outside the body from inside the body. Sincethe other aspects are the same as in the preceding embodiment, commonpoints will not be described and only different points will bedescribed.

The charging system according to the different embodiment, as shown inFIG. 12, has four direction detecting coils 19A-19D arrangedequidistantly at 90° intervals in the circumferential direction aroundthe power receiving coil 4, and a voltage detecting and coil identifyingcircuit 20 for detecting voltages produced on the direction detectingcoils 19A-19D as the charging electric power is transmitted from thepower transmitting coil 9, comparing levels of the detected voltages ofthe direction detecting coils 19A-19D to identify a direction detectingcoil located in a direction of displacement of the power transmittingcoil 9, and outputting it as a direction of coil displacement to thesecondary side control circuit 12. Differences in level among thedetected voltages of the direction detecting coils 19A-19D are producedaccording to a direction of displacement of the power transmitting coil9, and a direction of coil displacement is determined based on this.Therefore, the direction detecting coils 19A-19D and voltage detectingand coil identifying circuit 20 constitute the direction of coildisplacement detecting means.

In the secondary side control circuit 12, as shown in FIG. 13, numbersof pulses 10 to 13 are assigned to the respective direction detectingcoils 19A-19D. During a direction of coil displacement communicatingperiod added after the amount of coil displacement communicating periodin the detecting result communicating period, as shown in FIG. 14, acoil outputted from the voltage detecting and coil identifying circuit20 is transmitted outside the body from inside the body in a formconverted into the number of pulses, as in the case of communicating thecharge status of the electric double layer capacitor 6 outside the body.

On the other hand, in the feeding device 2, the voltage smoothingcircuit 14 and primary side control circuit 15 count the number ofpulses, detect a direction of coil displacement and report it on adirection of coil displacement display panel (not shown), as in the caseof detecting the charge status of the electric double layer capacitor 6transmitted outside the body.

In this embodiment, since the operator can know a direction of coildisplacement between the power receiving and power transmitting coils 4and 9, the coil displacement between the power receiving and powertransmitting coils 4 and 9 may be corrected easily.

This invention is not limited to the above embodiments, but may bemodified as follows:

(1) In both of the above embodiments, the storage means of the storagedevice 1 is the electric double layer capacitor 6. Instead of theelectric double layer capacitor 6, various rechargeable batteries (e.g.lithium battery) may be used as the storage means.

(2) In both of the above embodiments, the resonant condition is changedby changing the resistance of a resistance element of the resonancecircuit 13. The resonant condition may be changed by changing thecapacity of a capacitative element (capacitor) of the resonance circuit13.

(3) The charge status of the electric double layer capacitor 6, and theamount of coil displacement and the direction of coil displacementbetween the power receiving and power transmitting coils 4 and 9 aretransmitted outside the body in the number of the pulses or the level ofvoltage in both of the above embodiments. Alternatively, they may betransmitted outside the body by using and coding a plurality of pulsescontinuous in time.

(4) A power transmitting coil 9 of large diameter may be installed on abed in a hospital room, for charging the electric double layer capacitor6 of the storage device 1 embedded in the body of a bedridden patient.In the other aspects, such a modified embodiment may be the samecharging system as in both of the above embodiments.

(5) In both of the above embodiments, the charge status of the electricdouble layer capacitor 6, and the amount of coil displacement and thedirection of coil displacement between the power receiving and powertransmitting coils 4 and 9, are transmitted outside the body through thepower receiving and power transmitting coils 4 and 9. A charging system,in which the charge status of the electric double layer capacitor 6, andthe amount of coil displacement and the direction of coil displacementbetween the power receiving and power transmitting coils 4 and 9 aretransmitted outside the body through two coils disposed independently ofthe power receiving and power transmitting coils 4 and 9 may be cited asa modified embodiment.

(6) In the example shown in FIG. 12, the four direction detecting coils19A-19D are arranged around the power receiving coil 4 in order todetect a direction of coil displacement between the power receiving andpower transmitting coils 4 and 9. Alternatively, for example, the powerreceiving coil 4 may be constructed of four divided coils. That is, withfour divided power receiving coils are arranged adjacent each other in aplane, a displacement in a set position of the power transmitting coil 9will cause an imbalance in the outputs of the four power receivingcoils. Therefore, a direction of coil displacement between the fourpower receiving coils and power transmitting coils 9 may be known bycomparing the levels of the outputs of these four power receiving coils.

(7) In both of the above embodiments, the artificial organ is a cardiacpacemaker. Artificial organs for which this invention is usable may be,not only a cardiac pacemaker, may be an artificial heart, artificialpancreas, and artificial urinary bladder, for example.

INDUSTRIAL UTILITY

As described above, a contactless charging system for an artificialorgan, and a storage device and a feeding device for use with thissystem, according to this invention, are suitable for use withartificial organs such as a cardiac pacemaker, artificial heart,artificial pancreas, artificial urinary bladder and so on.

1. A contactless charging system for an artificial organ characterizedby comprising: (A) a storage device embedded as a whole in a body alongwith the artificial organ, and including power receiving coil meansacting as a secondary side coil in a pair of coil means for transferringpower, rectifying means for rectifying and outputting an AC received bythe power receiving coil means, storage means for storing output fromthe rectifying means as electric power for driving the artificial organ,charge status detecting means for detect a charge status of the storagemeans, and charge status transmitting means for transmitting outside thebody the charge status detected by the charge status detecting means;and (B) a feeding device provided separately from the storage device anddisposed as a whole outside the body, and including power transmittingcoil means acting as a primary side coil in said pair of coil means, ACoutput means for outputting the AC to the power transmitting coil means,charge status receiving means for receiving the charge statustransmitted outside the body from said charge status transmitting means,and charge status informing means for informing the charge statusreceived by the charge status receiving means.
 2. A contactless chargingsystem for an artificial organ as defined in claim 1, wherein: at leastone of the storage device and the feeding device includes amount of coildisplacement detecting means for detecting an amount of coildisplacement as an extent of a displacement occurring between the powerreceiving coil means and the power transmitting coil means, and thefeeding device includes amount of coil displacement informing means forinforming the amount of coil displacement detected by the amount of coildisplacement detecting means.
 3. A contactless charging system for anartificial organ as defined in claim 2, wherein: the amount of coildisplacement detecting means of said storage device includes a smoothingcircuit for smoothing a voltage at opposite ends of said power receivingcoil detecting means, and a secondary side control circuit fordetermining the amount of coil displacement based on a smoothed voltagevalue.
 4. A contactless charging system for an artificial organ asdefined in claim 2, wherein: the amount of coil displacement detectingmeans of said feeding device includes a smoothing circuit for smoothinga voltage at opposite ends of said power transmitting coil detectingmeans, and a primary side control circuit for determining the amount ofcoil displacement based on a smoothed voltage value.
 5. A contactlesscharging system for an artificial organ as defined in claim 2, wherein:the amount of coil displacement detecting means is disposed in thestorage device, the amount of coil displacement detected beingtransmitted outside the body along with the charge status by said chargestatus transmitting means.
 6. A contactless charging system for anartificial organ as defined in claim 5, comprising: display means fordisplaying the amount of coil displacement and the charge statustransmitted outside the body by said charge status transmitting means.7. A contactless charging system for an artificial organ as defined inclaim 1, wherein: at least one of the storage device and the feedingdevice includes direction of coil displacement detecting means fordetecting a direction of coil displacement as an extent of adisplacement occurring between the power receiving coil means and thepower transmitting coil means, and the feeding device includes directionof coil displacement informing means for informing the direction of coildisplacement detected by the direction of coil displacement detectingmeans.
 8. A contactless charging system for an artificial organ asdefined in claim 7, wherein: the direction of coil displacementdetecting means of said storage device includes a plurality of directiondetecting coils arranged at predetermined intervals around said powerreceiving coil means, and a secondary side control circuit fordetermining the direction of coil displacement based on voltages valuesdetected from the plurality of direction detecting coils.
 9. Acontactless charging system for an artificial organ as defined in claim7, wherein: the direction of coil displacement detecting means of saidstorage device includes a plurality of direction detecting coilsarranged at predetermined intervals around said power receiving coilmeans, and a primary side control circuit for determining the directionof coil displacement based on voltages values detected from theplurality of direction detecting coils.
 10. A contactless chargingsystem for an artificial organ as defined in claim 7, wherein: thedirection of coil displacement detecting means of said storage deviceincludes a plurality of divided power receiving coil means arrangedannularly, and a secondary side control circuit for determining thedirection of coil displacement based on voltages values detected fromthe respective power receiving coil means.
 11. A contactless chargingsystem for an artificial organ as defined in claim 7, wherein: thedirection of coil displacement detecting means of said storage deviceincludes a plurality of divided power receiving coil means arrangedannularly, and a primary side control circuit for determining thedirection of coil displacement based on voltages values detected fromthe respective power receiving coil means.
 12. A contactless chargingsystem for an artificial organ as defined in claim 7, wherein: thedirection of coil displacement detecting means is disposed in thestorage device, the direction of coil displacement detected beingtransmitted outside the body along with the charge status by said chargestatus transmitting means.
 13. A contactless charging system for anartificial organ as defined in claim 12, comprising: display means fordisplaying the direction of coil displacement and the charge statustransmitted outside the body by said charge status transmitting means.14. A contactless charging system for an artificial organ as defined inclaim 1, wherein: the charge status transmitting means of the storagedevice is arranged to transmit a result of detection of the chargestatus outside the body through power receiving coil means powertransmitting coil means acting as the pair of coil means fortransferring power.
 15. A contactless charging system for an artificialorgan as defined in claim 1, wherein: the storage means of said storagedevice is a rechargeable battery.
 16. A contactless charging system foran artificial organ as defined in claim 1, wherein: the storage means ofsaid storage device is an electric double layer capacitor.
 17. A storagedevice for use with a contactless charging system for an artificialorgan characterized in that: the storage device is the storage deviceset forth in claim
 1. 18. A feeding device for use with a contactlesscharging system for an artificial organ characterized in that: thefeeding device is the feeding device set forth in claim
 1. 19. Acontactless charging system for an artificial organ characterized bycomprising: (A) a storage device embedded as a whole in a body alongwith the artificial organ, and including power receiving coil meansacting as a secondary side coil in a pair of coil means for transferringpower, rectifying means for rectifying and outputting an AC received bythe power receiving coil means, storage means for storing output fromthe rectifying means as electric power for driving the artificial organ,charge status detecting means for detect a charge status of the storagemeans, and charge status transmitting means for transmitting outside thebody the charge status detected by the charge status detecting means;and (B) a feeding device provided separately from the storage device anddisposed as a whole outside the body, and including power transmittingcoil means acting as a primary side coil in said pair of coil means, ACoutput means for outputting the AC to the power transmitting coil means,charge status receiving means for receiving the charge statustransmitted outside the body from said charge status transmitting means,and charge status informing means for informing the charge statusreceived by the charge status receiving means; wherein the powerreceiving coil means included in said storage device is more than one,detecting means being provided for detecting, based on outputs fromthese plurality of power receiving coil means, an amount of coildisplacement as an extent of a displacement occurring between thesepower receiving coil means and said power transmitting coil means, and adirection of displacement from the amount of coil displacement; saidcharge status transmitting means further transmits outside the body saidamount of coil displacement detected by said detecting means and thedirection of displacement from the amount of coil displacement; and saidfeeding device further includes informing means for informing at leastone of the charge status of the said storage device, a state of coildisplacement and the directions of coil displacement.
 20. A contactlesscharging system for an artificial organ as defined in claim 19,characterized in that: the power transmitting coil means comprise fourtransmitting coil means arranged adjacent one another in a plane.